Can you take in too many electrolytes during endurance events?

Question

I know I can become subjected to hyponatremia by drinking too much water and not replenishing my electrolytes. But is the opposite possible? Can I put too MANY electrolytes into my body (while still putting in the correct amount of fluid) during an endurance event? I once had a Dr. tell me "you can never drink too much gatorade", indicating I would not overload the electrolytes in my body to an unhealthy or dangerous level. Is that true? Do I not have to worry about electrolyte overdose?

UPDATE: I should clarify that I'm asking the question for extreme endurance events, such as 100-mile and 24-hour races.

Answer 1

Yes, absolutely you can overdo it with electrolytes. It's called hypernatremia. The best resource I know of is the 9-way table by Karl King. This shows the effects of being under-, over- or normally hydrated and being under-, over- or normally salted. It shows what the symptoms are and what the treatment is. This table is really useful.

You can tell if you're in this state because salty foods will taste bad. Your body would be telling you to stop.

Gatorade is rather unlikely to get you into this state because it's isotonic. Its concentration is the same as blood so you would need to add external electrolytes to start getting into hypernatremia.

If you're looking at training for 100mi or 24hr events then you'll need to start experimenting with the regime that works for you. Gatorade probably won't because its strong sweet taste becomes unpalatable after a few hours.

Karl King is a scientist who studies these issues in details and supplies hydration and electrolyte products. He's a little controversial in the ultra world in that he's banned from the ultra mailing list for pushing those products without specifying that he has a financial interest in them.

Answer 2

The word here is you "probably" don't have to worry about overdosing on electrolytes if you are drinking premade sports drinks. They are of a concentration that you would probably not be able to drink any more long before the electrolytes would become an issue.

However, if you are drinking sports drinks and supplementing with salt tabs, or some of the other tricks long distance endurance athletes use to keep electrolyte supply up, then yes, it's certainly possible to take in too many electrolytes, which can result in anything from mild nausea to cramping to heart arrhythmias. (two electrolytes, sodium and potassium are what drive the beating of the heart.)

Also, if you have an underlying pathology, either known or unknown, that can have an effect on things like absorption and utilization.

So again, the key word is you "probably" have nothing to worry about if you stick to premade sports drinks, which for most endurance events are supplied on course.